1 files changed, 102 insertions, 0 deletions
diff --git a/src/3rdparty/resonance-audio/resonance_audio/dsp/gain.cc b/src/3rdparty/resonance-audio/resonance_audio/dsp/gain.cc
new file mode 100644
index 000000000..54e3fc216
--- /dev/null
+++ b/src/3rdparty/resonance-audio/resonance_audio/dsp/gain.cc
@@ -0,0 +1,102 @@
+/*
+Copyright 2018 Google Inc. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS-IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include "dsp/gain.h"
+
+#include "base/constants_and_types.h"
+#include "base/simd_macros.h"
+#include "base/simd_utils.h"
+
+namespace vraudio {
+
+float LinearGainRamp(size_t ramp_length, float start_gain, float end_gain,
+                     const AudioBuffer::Channel& input_samples,
+                     AudioBuffer::Channel* output_samples,
+                     bool accumulate_output) {
+  DCHECK(output_samples);
+  DCHECK_EQ(input_samples.size(), output_samples->size());
+  DCHECK_GT(ramp_length, 0U);
+
+  const size_t process_length = std::min(ramp_length, input_samples.size());
+  const float gain_increment_per_sample =
+      (end_gain - start_gain) / static_cast<float>(ramp_length);
+
+  float current_gain = start_gain;
+  if (accumulate_output) {
+    for (size_t frame = 0; frame < process_length; ++frame) {
+      (*output_samples)[frame] += current_gain * input_samples[frame];
+      current_gain += gain_increment_per_sample;
+    }
+  } else {
+    for (size_t frame = 0; frame < process_length; ++frame) {
+      (*output_samples)[frame] = current_gain * input_samples[frame];
+      current_gain += gain_increment_per_sample;
+    }
+  }
+
+  return current_gain;
+}
+
+void ConstantGain(size_t offset_index, float gain,
+                  const AudioBuffer::Channel& input_samples,
+                  AudioBuffer::Channel* output_samples,
+                  bool accumulate_output) {
+  DCHECK(output_samples);
+  const size_t input_size = input_samples.size();
+  DCHECK_EQ(input_size, output_samples->size());
+  DCHECK_LT(offset_index, input_size);
+
+  // Apply gain to samples at the beginning, prior to SIMD_LENGTH alignment.
+  const size_t unaligned_samples = SIMD_LENGTH - (offset_index % SIMD_LENGTH);
+  const size_t offset_index_simd =
+      std::min(input_size, offset_index + unaligned_samples);
+  if (accumulate_output) {
+    for (size_t i = offset_index; i < offset_index_simd; ++i) {
+      (*output_samples)[i] += input_samples[i] * gain;
+    }
+  } else {
+    for (size_t i = offset_index; i < offset_index_simd; ++i) {
+      (*output_samples)[i] = input_samples[i] * gain;
+    }
+  }
+
+  if (offset_index_simd == input_size) {
+    // Return if there are no remaining operations to carry out.
+    return;
+  }
+
+  const size_t aligned_length = input_size - offset_index_simd;
+  const float* aligned_input = &(input_samples[offset_index_simd]);
+  float* aligned_output = &(*output_samples)[offset_index_simd];
+
+  // Apply gain via SIMD operations.
+  if (accumulate_output) {
+    ScalarMultiplyAndAccumulate(aligned_length, gain, aligned_input,
+                                aligned_output);
+  } else {
+    ScalarMultiply(aligned_length, gain, aligned_input, aligned_output);
+  }
+}
+
+bool IsGainNearZero(float gain) {
+  return std::abs(gain) < kNegative60dbInAmplitude;
+}
+
+bool IsGainNearUnity(float gain) {
+  return std::abs(1.0f - gain) < kNegative60dbInAmplitude;
+}
+
+}  // namespace vraudio